Mononoble metal dithiolates, preparations containing them and their use

Abstract

The invention relates to mononoble metal dithiolates, more particularly water-soluble monogold(I) dithiolates, to their production and to their use for the production of noblemetal-containing decorations on firing-resistant substrates. The mononoble metal dithiolates represent a new class of water-soluble thiolates for use in organic-aqueous and essentially purely aqueous noble metal preparations for decoration purposes. The mononoble metal dithiolates correspond to the following formula: ##STR1## in which Em=Au(I), Ag(I), an equivalent of Pd(II), Pt(II) or Rh(III), Q=a tetravalent organic radical containing 2 to 10 carbon atoms, Y=a hydrophilic group from the series comprising --COOH, --COO - cat + or --COO--(CHR 1 --CHR 2 --O) m R 3 Z=Y or H or a group from the series comprising --OR', --SR', --SO 3 R', --NR' 2 , --NR 3 + X - .

We claim: 
     
       1. A mononoble metal dithiolate of the formula (A): ##STR9## in which Em is a noble metal selected from the group consisting of Au(I), Ag(I), Pd(II), Pt(II) and Rh(III), Q is a tetravalent organic radical containing 2 to 10 carbon atoms,   Y is a hydrophilic group selected from the group consisting of (1) --COOH, (2) --COO -  cat + , where cat +   is Li + , Na + , K + , NH 4   + , (C 1-3  alkyl) n  N +  H.sub.(4-n) or (hydroxy-(C 1-3 )-alkyl) n  N +  H.sub.(4-n) and n is an integer of 1 to 4, and (3) ##STR10## where R 1 , R 2  and R 3  may be the same or different and represent H or methyl and m is an integer of 1 to 12,   Z has the same meaning as Y or represents --H or a member selected from the group consisting of --OR', --SR', --SO 3  R', --NR' 2 , NR' 3   +  X - , where X -   is a mineral acid or carboxylic acid anion and R' is hydrogen or the group ##STR11## wherein R 1  is H or methyl and   m is an integer of 1 to 12.   
     
     
       2. A mononoble metal dithiolate as claimed in claim 1, wherein Em stands for gold or silver in the oxidation stage (I). 
     
     
       3. A mononoble metal dithiolate as claimed in claim 1 or 2, which is soluble in water and wherein at least one of Y and Z represents COO -  cat +   or wherein Y is a carboxyl group and Z is an amino group of the formula --NR' 2  capable of forming an inner salt with the carboxyl group and wherein cat +   and R' are as defined in claim 1. 
     
     
       4. A mononoble metal dithiolate as claimed in claim 1 or 2, wherein the organic radical Q is an aliphatic C 2-4  alkane tetrayl radical or a 5- or 6-membered cycloaliphatic tetrayl radical optionally containing an oxygen or imine ring member. 
     
     
       5. A mononoble metal dithiolate as claimed in claim 3, wherein the organic radical Q is an aliphatic C 2-4  alkane tetrayl radical or a 5- or 6-membered cycloaliphatic tetrayl radical optionally containing an oxygen or imine ring member. 
     
     
       6. A mononoble metal dithiolate as claimed in claim 1 or 2, which is monogold(I) or monosilver dimercaptosuccinic acid or a salt thereof. 
     
     
       7. A mononoble metal dithiolate as claimed in claim 3, which is monogold(I) or monosilver dimercaptosuccinic acid or a salt thereof. 
     
     
       8. A mononoble metal dithiolate as claimed in claim 4, which is monogold(I) or monosilver dimercaptosuccinic acid or a salt thereof. 
     
     
       9. A process for the production of a mononoble metal dithiolate of the formula (A'): ##STR12## in which Q, Z and Y are as defined in claim 1, which comprises reacting an Au(I) complex of the formula AuCl.R"SR'", where R"S'" is a thioether, with a substantially equivalent molar quantity of a thiol in the presence of a solvent, the thiol used being a thiol of the formula (B): ##STR13## in which Q, Y and Z are as defined in claim 1. 
     
     
       10. A process as defined in claim 9, wherein the thioether R"S'"is methionine. 
     
     
       11. A process for the production of a mono-noble metal dithiolate of formula A of claim 1, wherein Em represents Ag(I), Pd(II) or Pt(II) which comprises reacting a soluble salt of Ag(I), Pd(II) or Pt(II) with a thiol compound, of the formula B ##STR14## wherein Q, Y and Z are as defined in claim 1. 
     
     
       12. In a noblemetal-containing preparation for decorating a firing-resistant substrate, to produce a noble metal decoration, said preparation containing at least one noble metal thiolate, at least one polymeric organic binder, at least one solvent for the noble metal thiolate, at least one binder and, optionally, at least one auxiliary for adjusting the processing properties of the preparation and the optical and performance properties of the noblemetal-containing decoration to be produced therewith, the improvement wherein the preparation contains at least one mononoble metal dithiolate as defined in claim 1 as the noble metal thiolate. 
     
     
       13. A preparation as claimed in claim 12, wherein in the mononoble metal dithiolate Em stands for gold or silver in the oxidation stage (I). 
     
     
       14. A preparation as defined in claim 12, wherein the firing-resistant substrate is glass. 
     
     
       15. A preparation as claimed in claim 12, containing a polar organic solvent and water as the solvent component. 
     
     
       16. A preparation as defined in claim 15, wherein the polar organic solvent is selected from the group consisting of (1) C 2-4  glycols or C 1-4  monoethers thereof,   (2) oligo(C 2-4 ) glycols or C 1-4  monoethers thereof, and   (3) (C 2-3 ) hydroxycarboxylic acids and (C 1-3 ) alkyl esters thereof.   
     
     
       17. A preparation as claimed in claim 12, containing water as solvent and less than 2 wt. %, relative to the preparation, of organic solvent, a mono-noble metal dithiolate as defined in claim 1, which has at least one functional group capable of salt formation, in the form of an aqueous salt, a water-soluble polymeric organic binder and an effective quantity of a surfactant. 
     
     
       18. A preparation according to claim 12, wherein the polymeric organic binder is selected from the group consisting of polyvinylpyrrolidone homo- or copolymers, polyacrylic acid homo- or copolymers, polymethacrylic acid homo- or copolymers, water-soluble cellulose ethers, and mixtures thereof. 
     
     
       19. A preparation according to claim 12, containing a salt prepared from a mono-noble metal dithiolate containing at least one carboxyl group, and a primary, secondary or tertiary amine or an N-heterocyclic base. 
     
     
       20. A preparation according to claim 12, wherein the mono-noble metal dithiolate is present in the form of a salt with tri(C 1  to C 3 )alkylamine or mono-, di- or triethanolamine and the preparation additionally contains at least one auxiliary substance to adjust the optical and service properties of the decoration to be produced and/or the processing characteristics of the preparation. 
     
     
       21. A preparation according to claim 20, containing a salt of monogold(I) dimercaptosuccinic acid. 
     
     
       22. A preparation according to claim 17, containing as surfactant 0.1 to 2.0 wt. %, of a polyoxyethylene-polydimethylsiloxane. 
     
     
       23. A preparation according to claim 22, wherein the amount of the surfactant is 0.2 to 1.0 wt. %. 
     
     
       24. A preparation according to claim 17, wherein the surfactant is an alkylbenzene sulphonate with 8 to 14 C atoms in the alkyl group in the form of a salt with an amine in a quantity of 0.1 to 2 wt. %. 
     
     
       25. A preparation according to claim 24, wherein the amount of the surfactant is 0.2 to 1.0 wt. %. 
     
     
       26. In a transfer for producing noble-metal-containing decorations on firing-resistant substrates, said transfer containing in a decoration layer one or more noble metal thiolates and one or more polymeric organic binders and, optionally, at least one auxiliary from the production of the transfer and for influencing the optical properties and performance properties of the noble-metal-containing decoration to be produced, the improvement wherein a mononoble metal dithiolate as defined in claim 1 is present in uniform distribution as the noble metal thiolate in the decoration layer. 
     
     
       27. In a process for decorating a stovable substrate by applying a preparation containing a noble metal thiolate or a transfer containing this preparation in a dry state onto the substrate and stoving at 400° to 900° C., the improvement wherein a preparation according to claim 12 or a transfer containing this preparation is used. 
     
     
       28. A process according to claim 27, wherein the stovable substrate is glass.